Antimicrobial coating system

ABSTRACT

An antimicrobial coating system, a film-forming composition, and an antimicrobial film. In some embodiments, the antimicrobial coating system can include a film-forming composition comprising a polymer having an effective molecular weight, and an effective amount of an antimicrobial agent dispersed within the polymer. The film-forming composition can form a water-insoluble, biocidal antimicrobial film when applied to a surface.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This is a continuation of U.S. patent application Ser. No. 12/097,334,filed Dec. 14, 2006, which is a national stage filing under 35 U.S.C.§371 of PCT Application No. PCT/US2006/047779, which claims priority toU.S. Provisional Patent Application No. 60/743,037, filed Dec. 14, 2005,and U.S. Provisional Patent Application No. 60/743,038, filed Dec. 14,2005, the disclosures of all of which are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to antimicrobial coatings. In particular,the present invention relates to removable antimicrobial coatings foruse on surfaces to reduce the risk of contamination by microorganisms.

BACKGROUND

Contamination by microorganisms can have dramatic impact on human lifeand health.

During everyday routines, people continuously come into contact with avariety of surfaces that are contaminated with one or more types ofmicroorganisms, some of which may be pathogens. Such surfaces mayinclude countertops, tables, and food preparation surfaces inrestaurants, splash guards and conveyor belts in food processing plants,public facilities, display applications, and a variety of surfaces inhealthcare settings. Contamination with pathogenic microorganisms insuch locations may result in the spread of disease and infections topeople, which correspondingly endangers human lives and increases healthcare costs.

To counter the spread of undesired microorganisms, frequently touched,potentially contaminated surfaces are typically cleaned and sanitized ona regular basis. While this provides an immediate reduction inconcentration of microorganisms on given surfaces, the surfaces must berepeatedly cleaned and sanitized on a frequent basis to continue toprevent contamination by microorganisms. One reason for this is becausemany antimicrobial materials used for cleaning and sanitation becomedeactivated when the surface is dried. In addition, many articles usedto wipe visible dirt from surfaces may recontaminate the wiped surfacewith microorganisms that will grow and cause a cross-contaminationhazard. For example, tables and food preparation surfaces at restaurantsare continuously wiped with a sponge or towel to remove excessconsumables and garbage. The article used for wiping frequently harborspathogenic microorganisms that are transferred to the wiped surface.

SUMMARY

Some aspects of the present invention provide an antimicrobial coatingsystem. The antimicrobial coating system can include a film-formingcomposition comprising a polymer having an effective molecular weight,and an effective amount of an antimicrobial agent dispersed within thepolymer. The film-forming composition can form a water-insoluble,biocidal antimicrobial film when applied to a surface.

In some aspects of the present invention, a film-forming composition isprovided. The film-forming composition can include a polymer and aneffective amount of an antimicrobial agent dispersed within the polymer.The polymer can include at least one of acrylic, urethane, polyvinylalcohol having an effective molecular weight, and combinations thereof.The antimicrobial agent can include at least one of a fatty acidmonoester, a fatty acid monoether, a transition metal ion-containingcompound, a quaternary ammonium-containing compound, a biguanide, andcombinations thereof.

Some aspects of the present invention provide an antimicrobial filmcomprising a polymer having an effective molecular weight, and aneffective amount of an antimicrobial agent. The antimicrobial film canbe water-insoluble and biocidal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of an antimicrobial film of the presentinvention disposed on a surface.

FIG. 2 is a side sectional view of the antimicrobial film disposed onthe surface, with a remover composition of the present invention beingdeposited on the antimicrobial film.

FIG. 3 is a top perspective view of a hand of a user removing theantimicrobial film from the surface with a wipe article.

FIG. 4 is a top perspective view of an article in use for applying anantimicrobial coating system of the present invention to a surface toform an antimicrobial film of the present invention.

While the above-identified drawings set forth several embodiments of theinvention, other embodiments are also contemplated, as noted in thediscussion. In all cases, this disclosure presents the invention by wayof representation and not limitation. It should be understood thatnumerous other modifications and embodiments can be devised by thoseskilled in the art, which fall within the scope and spirit of theprinciples of the invention. The figures may not be drawn to scale. Likereference numbers have been used throughout the figures to denote likeparts.

DETAILED DESCRIPTION

FIG. 1 is a side sectional view of antimicrobial film 10 disposed onsurface 12, where antimicrobial film 10 is formed by a film-formingcomposition that can form a first part of a two-part antimicrobialcoating system of the present invention. As discussed below, the secondpart of the antimicrobial coating system is a remover composition (notshown in FIG. 1) that includes a solvent suitable for removingantimicrobial film 10 from surface 12.

Surface 12 may be any surface that may incur contamination bymicroorganisms, such as table and counter tops, food preparationsurfaces, surfaces found in publicly used locations and facilities(e.g., public telephones, public transportation, and public lavatoryfacilities), touch-screen displays, door handles, light switches, andsurfaces found in healthcare settings (e.g., bed rails and side tables).While surface 12 is shown as a flat, planar surface, antimicrobial film10 may also be coated on curved and irregular shaped surfaces. As usedherein and in the appended claims, the term “microorganism,” “microbe,”or a derivative thereof, is used to refer to any microscopic organism,including without limitation, one or more of bacteria, viruses, algae,fungi and protozoa. In some cases, the microorganisms of particularinterest are those that are pathogenic, and the term “pathogen” is usedherein to refer to any pathogenic microorganism.

As described above, antimicrobial film 10 is derived from a film-formingcomposition that is coated onto surface 12, where the film-formingcomposition includes a polymer of an effective molecular weight toprovide a water-insoluble antimicrobial film 10 and an effective amountof one or more antimicrobial agents to reduce microorganismcontamination. In some embodiments, the antimicrobial agents aredispersed within the polymer in a releasable manner, which allows theantimicrobial agents to be released from antimicrobial film 10 at aneffective diffusion rate to reduce microorganism contamination onsurface 12. In some embodiments, reducing microorganism contaminationincludes providing biocidal activity. As used herein and in the appendedclaims, the term “biocidal” is used to describe an antimicrobial film 10that kills microorganisms that come into contact with the antimicrobialfilm 10. As a result, biocidal activity is distinguishable over systemsthat merely provide inhibition of microorganism growth, because a filmthat inhibits growth and/or reproduction of microorganisms does notnecessarily kill the microorganisms. In some embodiments, as furthertaught by the examples, biocidal activity, and particularly, extendedbiocidal activity (e.g., after 24 hours) can be demonstrated by themicrobial load reductions exhibited by the antimicrobial film 10, whentested pursuant to ASTM E2180-01.

While disposed on surface 12, antimicrobial film 10 is resistant toremoval by moderate frictional forces, such as frictional forces appliedwhen a user uses a wipe article (e.g., a cloth towel or sponge) to wipefood or waste from surface 12. This allows antimicrobial film 10 toprovide antimicrobial protection to surface 12 without the risk ofaccidentally being removed while surface 12 is wiped clean. In someembodiments, antimicrobial film 10 is water-insoluble.

As used herein and in the appended claims, the term “water-insoluble” isused to refer to an antimicrobial film that does not dissolve (i.e.,form a homogeneous solution) after 30 minutes of being placed in DIwater at room temperature with no stirring. One example of a method fortesting water-insolubility is by forming the antimicrobial film onto arelease liner, peeling the antimicrobial film from the release liner andsubmerging the antimicrobial film in DI water at room temperature for 30minutes with no stirring. If, after 30 minutes, in these conditions, atleast a portion of the antimicrobial film still remains intact and hasnot gone into solution, the antimicrobial film is “water-insoluble.” Asa result, if an antimicrobial film swells in water under theseconditions, but does not dissolve to form a homogeneous solution, theantimicrobial film is “water-insoluble.”

When desired, antimicrobial film 10 may be removed from surface 12 witha remover composition, and a fresh coating of antimicrobial film 10 maybe applied to provide continuing antimicrobial protection to surface 12.When removal of antimicrobial film 10 is desired, the removercomposition may be applied, and antimicrobial film 10 may then be wipedoff from surface 12 under moderate frictional forces. As a result, theantimicrobial coating system of the present invention is a convenientsystem for applying and removing durable antimicrobial coatings havingbiocidal activity to and from a variety of surfaces.

Suitable polymers for use in the film-forming composition ofantimicrobial film 10 include water-soluble polymers, organicsolvent-soluble polymers, and water-based polymer dispersions. Examplesof water-soluble polymers include polyvinyl alcohols,polyvinylpyrrolidones, polyethylene oxides, sulfonated polyurethanes,copolymers thereof, and combinations thereof. Suitable commerciallyavailable polyvinyl alcohols include those available from J. T. Baker,Phillipsburg, N.J., and from Sigma-Aldrich Company, St. Louis, Mo.Suitable commercially available polyvinylpyrrolidones include thoseavailable from J. T. Baker, and those available under the tradedesignations “PVP-Kxx” from Peakchem, ZheJiang, China, where the “xx”number after the letter K indicates the average molecular weight (in1,000s of Daltons) of the polymer (e.g., “PVP-K90” and “PVP-K30”).

Suitable commercially available polyethylene oxide polymers includethose available under the trade designation “POLYOX” from Dow ChemicalCo., Midland, Mich. Suitable water-soluble polymers may have a widerange of molecular weights, where the molecular weight generallydetermines the product performance. For example, if the polymermolecular weight is too low, the film coating may be tacky and easilyremovable (i.e., has poor durability and is water-soluble).Alternatively, if the molecular weight of the polymer is too high, thecoating solution exhibits poor solubility, which results in the filmbeing difficult to remove. For applications in which the antimicrobialfilm 10 will need to be removed and replenished from time to time,suitable molecular weights provide good film durability,water-insolubility, and relative ease of removal by an appropriateremover composition. That is, in some embodiments, an effectivemolecular weight refers to a molecular weight that allows the resultingantimicrobial film 10 to be water-insoluble. For example, in someembodiments, an effective molecular weight of polyvinyl alcohol is atleast about 100,000 Daltons, particularly, at least about 120,000, andmore particularly, at least about 150,000 Daltons.

Suitable organic solvent-soluble polymers include polyurethanes, acrylicpolymers, polyamides, copolymers thereof, and combinations thereof.Commercially available solvent-based polyurethanes include thoseavailable under the trade designation “PERMUTHANE” from Stahl USA,Peabody, Mass. (e.g., “SU26-248”, which is an aliphatic polyurethane intoluene). Other suitable polyurethanes include those commerciallyavailable under the trade designations “ESTANE” from B.F. Goodrich,Cleveland, Ohio (e.g., “Estane 5715” and “Estane 5778”), and “MORTHANE”from Huntsman Polyurethanes, Ringwood, Ill. (e.g., “CA118” and “CA237”polyester polyurethanes). Additional suitable polymers include thosecommercially available under the trade designation “U-371” from DSMNeoResins, Wilmington, Mass.

Examples of water-based polymer dispersions include polyurethanes,polyureas, polyacrylics, polyethers, polyester, and copolymers thereofand combinations thereof. Suitable aqueous dispersions include urethanessuch as those commercially available under the trade designation“NEOREZ” from DSM NeoResins, Wilmington, Mass. (e.g., “NEOREZ R-960” and“NEOREZ R-9699”); acrylics such as those commercially available underthe trade designation “NEOCRYL” from DSM NeoResins (e.g., “NEOCRYLXK-90”, “NEOCRYL XK-96”, and “NEOCRYL XK-95”); and acrylic urethanecopolymers such as those commercially available under the tradedesignation “NEOPAC” from DSM NeoResins. Additional suitable water-basedurethanes include those commercially available under the tradedesignations “RU-077” and “RU-075” from Stahl USA, Peabody, Mass.

Water-soluble materials can be suitable for use in situations whereantimicrobial film 10 remains dry until the intended removal with awater-based remover composition. The above-listed materials may also bepartially or fully cross-linked to improve the mechanical structure ofthe polymer, and to reduce the water solubility of such materials.Polymers having reduced water solubility are beneficial for use onsurfaces (e.g., surface 12) that come into contact with water (e.g.,surfaces that are rinsed or soaked with water). To initiate thecross-linking, the polymer may include curing agents, such as chainextension agents, chemical cross-linking agents, and radiationcross-linking agents (e.g., photoinitiators).

To initiate the cross-linking, the film-forming composition may includecross-linking agents, such as chain extension agents and chemicalcross-linking agents. Examples of cross-linking agents includeisocyanates such as those commercially available under the tradedesignation “DESMODUR” from Bayer AG, Pittsburgh, Pa.; aziridinecrosslinkers such as those commercially available under the tradedesignation “CX-100” from DSM NeoResins, Wilmington, Mass.; and thosecommercially available under the trade designation “XR-2500” from StahlUSA, Peabody, Mass. Suitable chain extension agents includecarbodiimides such as those commercially available under the tradedesignation “EX62-944”, and melamines such as those commerciallyavailable under the trade designation “XR-9174”, both from Stahl USA.

Examples of particularly suitable cross-linkable polymer compositionsinclude self cross-linking polymer dispersions, where the depositedcoating self cross-links upon drying to form a durable, water-insolublecoating layer. Self cross-linking polymer dispersions typically containside groups that react to form chemical bonds via condensationpolymerizations, which take place upon evaporation of water. Selfcross-linking polymer dispersions offer the advantage of formingantimicrobial films (e.g., antimicrobial film 10) that are solventresistant without requiring cross-linking agents. Various types ofcross-linking agents can pose potential health risks because they aresmall, solvent-borne, organic molecules (e.g., isocyanates).

Examples of self cross-linking urethane dispersions includepolyester-urethanes that are terminated by hydrolysable silyl groups andcontain solubilizing sulfonic acid functional groups. Suchpolyester-urethanes are described in Krepski, et al., U.S. Pat. No.5,929,160, which is incorporated by reference in its entirety.Additional examples of suitable self cross-linking urethane dispersionsinclude polyurethane water-based dispersions containing hydroxyl groupsto accomplish the self cross-linking function. Suitable hydroxylgroup-based polyurethanes include those prepared pursuant to the processdescribed in Mazanek et al., U.S. Pat. No. 7,049,367, which isincorporated by reference in its entirety. Even further additionalexamples of suitable self cross-linking urethane dispersions includepolyurethane polymer hybrid dispersions based on oxidatively dryingpolyols, such as those disclosed in Ingrisch et al., U.S. Pat. No.6,462,127, which is incorporated by reference in its entirety.

Examples of commercially available self cross-linking polymers includedispersions sold under the trade designations “RHEOPLEX” and “ROVACE”available from Rohm and Haas Company, Philadelphia, Pa., which aretypically used as binders for textile and non-woven substrates for theprotection of color dyes applied to the substrates. Exemplarycompositions include the trade designated “RHEOPLEX HA-12” (non-ionicdispersion with glass transition temperature of about 19° C.) and“RHEOPLEX TR-407” (anionic dispersion with glass transition temperatureof 34° C.), both of which exhibit good wash durability and chemicalresistance. Additional examples of commercially available selfcross-linking polymers include the trade designated “NEOREZ R-551”polyether-based polymers and “NEOCRYL XK-98” acrylic emulsion polymers,both of which are available from DSM NeoResins, Wilmington, Mass. The“NEOCRYL XK-98” acrylic emulsion polymers are particularly suitablebecause they provide good adhesion to most substrates and exhibit highgloss and block resistance.

Suitable concentrations of the polymer in the film-forming compositionof antimicrobial film 10, after application and drying of the film,include any concentration that is effective for dispersing andcontaining the antimicrobial agents. Examples of suitable concentrationsof the polymer in the film-forming composition of antimicrobial film 10range from about 50% by weight to about 99.9% by weight, withparticularly suitable concentrations ranging from about 70% by weight toabout 99% by weight, and with even more particularly suitableconcentrations ranging from about 90% by weight to about 95% by weight.

Suitable antimicrobial agents for use in the film-forming composition ofantimicrobial film 10 include any inorganic or organic antimicrobialagent that is effective for reducing microbial contamination. Examplesof suitable antimicrobial agents include transition metal ion-containingcompounds, (e.g., silver, zinc, copper, gold, tin and platinum-basedcompounds), fatty acid monoesters/monoethers, triclosan, peroxides,iodines, quaternary ammonium-containing compounds, biguanides, complexesthereof (e.g., iodophores), derivatives thereof, and combinationsthereof.

Examples of suitable silver-containing compounds include silver sulfate,silver acetate, silver chloride, silver lactate, silver phosphate,silver stearate, silver thiocyanate, silver proteinate, silvercarbonate, silver nitrate, silver sulfadiazine, silver alginate, silvernanoparticles, silver-substituted ceramic zeolites, silver complexedwith calcium phosphates, silver-copper complexed with calciumphosphates, silver dihydrogen citrates, silver iodines, silver oxides,silver zirconium phosphates, silver-substituted glass, and combinationsthereof.

Suitable commercially available silver zeolite-containing compoundsinclude those sold under the trade designation “AGION” from AgIONTechnologies Inc., Wakefield, Mass.; those available under the tradedesignations “IRGAGUARD B5000” and “IRGAGUARD B8000”, which are based onAgZn zeolites supplied by Ciba Specialty Chemicals, Tarrytown, N.Y.; aswell as those available under the trade designation “ALPHASAN”, whichare silver sodium hydrogen zirconium phosphates, supplied by MillikenChemicals, Spartanburg, S.C. Suitable commercially available silverchloride-containing compounds include those available under the tradedesignation “JMAC” from Clariant Corporation, Charlotte, N.C.

Examples of suitable commercially available organic antimicrobial agentsinclude polymeric quaternary ammonium salts such as 2-butenyldimethylammonium chloride polymers commercially available under the tradedesignation “POLYQUAT” from Arch Chemicals, Inc., Norwalk, Conn.;phenolic compounds such as phenol and its derivatives, parabens, andtriclosan, which has the chemical formula 2,4,4′-trichloro-2′-hydroxydiphenyl ether, and is commercially available from Ciba SpecialtyChemicals, Tarrytown, N.Y.;poly(iminoimidocarbonylimidocarbonyliminohexamethylene hydrochlorides),commercially available under the trade designation “VANTOCIL P” fromArch Chemicals, Inc., Norwalk, Conn.; polyhexamethylene biguanides,antimicrobial lipids such as those disclosed in Scholz et al., U.S.Publication No. 2005/0089539, which is incorporated herein by reference,antimicrobial acids (e.g., fatty acids, benzoic acids, and salicylicacids), antimicrobial natural oils (e.g., tea tree oils, and grape fruitseed extracts), and combinations thereof. Additional suitable organicantimicrobial agents include organic salts of transition metals (i.e.,organometallic antimicrobial agents), such as silver salts (e.g., silverlactate), copper salts (e.g., copper napthenate), zinc salts, and tinsalts (e.g., trialkyl tin hydroxides and triaryl tin hydroxides).

Suitable antimicrobial lipids include, for example, fatty acidmonoesters/monoethers. In some embodiments, the fatty acidmonoesters/monoethers suitable for the antimicrobial agent areconsidered food grade and recognized as safe (GRAS) by the U.S. Food andDrug Administration (FDA). Such fatty acid monoesters/monoethers may bederived from C8 to C12 fatty acids such as glycerol monoesters ofcaprylic acid, capric acid, and lauric acid; propylene glycol monoestersof caprylic acid, capric acid, and lauric acid; and combinationsthereof. Examples of suitable fatty acid monoesters include, but are notlimited to, glycerol monolaurate commercially available under the tradedesignation “LAURICIDIN” from Med-Chem Laboratories, East Lansing,Mich.; glycerol monocaprylate commercially available under the tradedesignation “POEM M-100” from Riken Vitamin Ltd., Tokyo, Japan; glycerolmonocaprate commercially available under the trade designation “POEMM-200” from Riken Vitamin Ltd.; propylene glycol monolaurate, propyleneglycol monocaprylate, and propylene glycol monocaprate, all commerciallyavailable from Uniquema International, Chicago, Ill.; and combinationsthereof.

Examples of suitable concentrations of the fatty acidmonoesters/monoethers range from about 1.0% to about 30.0% by weight.Examples of particularly suitable concentrations of the fatty acidmonoesters/monoethers in the composition range from about 5.0% to about20.0% by weight.

The antimicrobial agent may also include an enhancer and/or a surfactantfor use with the fatty acid monoesters/monoethers, as discussed inAndrew et al., PCT application No. WO 00/71183, entitled “AntimicrobialArticles,” and in Andrews et al., PCT Application No. WO01/43549,entitled “Fruit, Vegetable, and Seed Disinfectants,” both of which areincorporated herein by reference in their entireties.

Suitable concentrations of the antimicrobial agents in the film-formingcomposition of antimicrobial film 10 include any concentration that iseffective for providing biocidal activity. This may vary depending onthe type of antimicrobial agent used. Examples of suitableconcentrations of the antimicrobial agents in the film-formingcomposition of antimicrobial film 10 range from about 0.1% by weight toabout 20% by weight, with particularly suitable concentrations rangingfrom about 1% by weight to about 10% by weight.

In some embodiments, the antimicrobial agent may at least partiallyinteract with the polymer (i.e., form non-covalent bonds (e.g., ionicbonds, hydrogen bonds, matrix interactions, etc.) or covalent bonds withthe polymer) so as not to be sufficiently available to provide biocidalactivity to microorganisms that come into contact with the antimicrobialfilm 10. In other words, the resulting antimicrobial film may not have asufficient surface concentration of the antimicrobial agent to providebiocidal activity. In such embodiments, a higher concentration ofantimicrobial agent may be needed to provide biocidal activity. As aresult, in some embodiments, an effective amount of antimicrobial agentis an amount that provides biocidal activity to microorganisms that comeinto contact with the antimicrobial film 10.

A “sufficiently available” antimicrobial agent or a “sufficient surfaceconcentration” of the antimicrobial agent in the antimicrobial film 10is sometimes used to refer to an antimicrobial film having microbialload reductions of at least 90% against gram positive or gram negativepathogens when tested pursuant to ASTM E2180-01, particularly, microbialload reductions of at least 90% against gram positive and gram negativepathogens when tested pursuant to ASTM E2180-01, particularly, microbialload reductions of at least 99% against gram positive or gram negativepathogens when tested pursuant to ASTM E2180-01, and more particularly,microbial load reductions of at least 99% against gram positive and gramnegative pathogens when tested pursuant to ASTM E2180-01.

The film-forming composition may also include fast-acting antimicrobialagents that may not provide antimicrobial activity over extended periodsof time, but which provide fast antimicrobial activity of a relativelyshort duration upon application of the film-forming composition tosurface 12. Examples of suitable fast-acting antimicrobial agentsinclude quaternary ammonium salts, benzalkonium chlorides, biguanidecompounds (e.g., halogenated hexidines such as chlorhexidine,chlorhexidine gluconate, and chlorhexidine acetate), alcohols (e.g., lowmolecular weight alcohols such as ethyl alcohol and isopropyl alcohol),bleach, hydrogen peroxide, urea hydrogen peroxide, hydrogen peroxidestabilized in a sodium pyrophosphate matrix, hydrogen peroxide chelatedin polyvinylpyrrolidone, and combinations thereof. Examples of suitablecommercially available quaternary ammonium salts include didecyldimethyl ammonium chlorides available under the trade designation “BTC1010” from Stepan Company, Northfield, Ill., and under the tradedesignation “BARDAC 2250” from Lonza Group Ltd., Valais, Switzerland;dialkyl dimethyl ammonium chlorides available under the tradedesignation “BARDAC 2050 also from Lonza Group Ltd.; and alkyl dimethylbenzyl ammonium chloride available under the trade designation “BARQUATMB-50” also from Lonza Group Ltd.

Suitable concentrations of the fast-acting antimicrobial agents in thefilm-forming composition of antimicrobial film 10 include anyconcentration that is effective for reducing microbial contamination,and may depend on the type of fast-acting antimicrobial agent used. Forexample, when the fast-acting antimicrobial agent is an alcohol,suitable concentrations of the alcohol in the film-forming compositionrange from about 20% by weight to about 80% by weight, with particularlysuitable concentrations ranging from about 40% by weight to about 60% byweight. Examples of suitable concentrations of the antimicrobial agentsin the film-forming composition of antimicrobial film 10 when quaternaryamines are used range from about 0.001% by weight to about 10% byweight, with particularly suitable concentrations ranging from about0.1% by weight to about 5% by weight.

The film-forming composition may also include surfactants and thickenersto modify wetting and flow properties. Examples of suitable surfactantsinclude the trade designated “SURFONIC L” series surfactantscommercially available from Huntsman Corporation, Salt Lake City, Utah;and the trade designated “ZONYL” surfactants commercially available fromE. I. du Pont de Nemours and Company. Examples of suitable thickenersinclude starch, gum arabic, guar gum, and carboxymethylcellulose. Aparticularly suitable thickening agent is commercially available underthe trade designation “NEOCRYL-A1127” from DSM NeoResins, Wilmington,Mass. Examples of suitable total concentrations of surfactants andthickeners in the film-forming composition of antimicrobial film 10range from about 1% by weight to about 20% by weight, with particularlysuitable total concentrations ranging from about 5% by weight to about10% by weight.

Additional optional components that may be incorporated into thefilm-forming composition include buffering agents and pH adjustingagents, fragrances or perfumes, dyes and/or colorants, solubilizingmaterials, defoamers, lotions and/or mineral oils, essential oils,enzymes, bleaching agents, preservatives, indicator dyes, andcombinations thereof. Examples of suitable total concentrations of theoptional components in the film-forming composition of antimicrobialfilm 10 range from about 1% by weight to about 20% by weight, withparticularly suitable total concentrations ranging from about 1% byweight to about 5% by weight. The film-forming composition ofantimicrobial film 10 may contain a dye to allow color tinting ofantimicrobial film 10 if desired.

Tinted films allow the end user to visually verify the film coverage ofsurface 12 and, after applying the remover composition, visually ensurethat all of antimicrobial film 10 has been removed from surface 12.Furthermore, indicator dyes provide color to the formulation allowing auser to visually verify the film coverage of surface 12, but the colordisappears upon drying (e.g., upon exposure to air) within a short timeperiod (e.g., few seconds or minutes) leaving a colorless film. Examplesof suitable indicator dyes include dyes based on phthalein chemistry,such as phenolphthalein (pink), thymolphthalein (blue), ando-cresolphthalein (purple), all of which are obtainable fromSigma-Aldrich Chemical Company, Saint Louis, Mo. Such indicator dyesalso allow a user to check that antimicrobial film 10 is still intact bywetting the surface 12. For example, in some embodiments, ifantimicrobial film 10 including the indicator dye is still intact on thesurface 12, the surface 12 will change color upon wetting (e.g., withwater, a high pH solution (such as WINDEX-brand glass cleaner solution),an ammonia solution, or whatever substance to which the indicator dye issensitive). This would indicate to the user, for example, thatantimicrobial film 10 is still applied to the surface 12.

The film-forming composition of antimicrobial film 10 may be formed byblending the antimicrobial agent, the polymer, and any optionalcomponents together. This may be performed as a solution in a solvent,where the solvent is selected to substantially dissolve or disperse theantimicrobial agent, the polymer, and any optional components. Examplesof suitable solid concentrations in the solvent for the resultingfilm-forming composition range from about 5% by weight to about 50% byweight. For water-based polymer dispersions, higher concentrations ofsolids may be achieved without an increase in the solution viscosity.Accordingly, particularly suitable solid concentrations in the solventfor water-based polymer dispersions range from about 10% to about 40% byweight. For non-dispersion water-based coatings, and for solvent-basedcoatings, particularly suitable solid concentrations in the solventrange from about 5% to about 20% by weight.

The film-forming composition may then be applied to surface 12 and driedto form antimicrobial film 10. The film-forming composition may beapplied to surface 12 in a variety of manners, such as by spraying,brushing, rod coating, or by wiping the film-forming composition ontosurface 12 with a wipe article.

For example, FIG. 4 is a top perspective view of an article 30 beingwiped across surface 12 by hand 16 of a user. Article 30 is a wipearticle that includes a substrate and a film-forming compositionimpregnated within the substrate. As the user wipes article 30 acrosssurface 12, the film-forming composition is extracted from the substrateof article 30 and deposits on surface 12. This forms a thin, continuousantimicrobial film 10 on surface 12.

The substrate of article 30 may be any type of woven, non-woven,knitted, foam, or sponge substrate, or combinations thereof, that iscapable of being impregnated with the film-forming composition. Thesubstrate may consist of a single layer or multiple layers of one ormore materials. Non-woven substrates are particularly suitable becauseof their utility in the manufacture of cleaning and scouring articles.

Because the film-forming composition is extracted from the substrateduring use, article 30 is particularly suitable as a disposable wipe(i.e., article 30 may be formed from substrate materials intended to bediscarded after use). Examples of suitable disposable wipe materials forthe substrate of article 30 include spun-bond and spun-lace non-wovenmaterials having a basis weight ranging from about 15 grams/meter² toabout 75 grams/meter². Such materials are generally made of syntheticpolymers, natural polymers, and combinations thereof. Suitable syntheticpolymers include rayon polyester, polyethylene terephthalate (PET),polyvinyl chloride, polyacrylamide, polystyrene, polyethersulfone,acrylics and acrylic copolymers, rayon, polyolefins (e.g.,polypropylene), and combinations thereof. Suitable natural polymersinclude wood pulp, cotton, cellulose, rayon, and combinations thereof.

In alternative embodiments, article 30 may be formed from materials usedfor semi-disposable or reusable wipes. Examples of suitablesemi-disposable wipe materials for the substrate of article 30 includespun-lace non-woven materials having a basis weight ranging from about75 grams/meter² to about 250 grams/meter². Such materials may be formedfrom fibers or microfibers of polyester, polyamide, viscose, orcombinations thereof. Examples of suitable reusable wipe materials forthe substrate of article 30 include knitted, woven, thermo-bonded,latex-coated, and chamois-type materials having a basis weight rangingfrom about 100 grams/meter² to about 300 grams/meter². Such materialsmay be formed from fibers or microfibers of polyester, rayon, viscose,polypropylene, natural fibers, polyamides, or combinations thereof.

Examples of suitable commercially available wipe materials include thosesold under the trade designation “SONTARA”, non-woven fabrics availablefrom Du Pont such as SONTARA 8001 (100% polyester substrate) and SONTARA8100 (50% polyester/50% Dacron). Other suitable wipe materials includethose designated as M001, M022, and M017, and are 100% spunlacedpolyester materials available from Polymer Group Inc., Wilmington, Del.Other polyester substrate materials can be obtained from Jacob HolmsIndustries under the designation 350160 and 10203-003.

In some embodiments, article 30 is glove-shaped to receive hand 16 ofthe user. This provides a convenient means for the user to wipe article30 across surface 12 to extract the film-forming composition. In someembodiments, the glove-shaped article 30 includes a barrier layer (e.g.,a flexible polymeric layer) between the substrate containing thefilm-forming composition and the hand 16 of the user. This can inhibitcontact between the film-forming composition and hand 16 of the user,thereby reducing the risk of irritating the skin of hand 16.

The film-forming composition that is impregnated within the substrateincludes a polymer, one or more antimicrobial agents, and a solvent. Insome embodiments, the polymer and the antimicrobial agent aresubstantially dissolved in the solvent, and the solvent is impregnatedwithin the substrate, thereby retaining the polymer and theantimicrobial agents (and any optional components) within the substrate.Examples of suitable concentrations of the film-forming composition inarticle 10, prior to extraction, range from about 50% by weight to about500% by weight of the substrate, based on a dry weight of the substrate.Examples of particularly suitable concentrations of the film-formingcomposition in article 10, prior to extraction, range from about 100% byweight to about 400% by weight of the substrate, based on a dry weightof the substrate.

The film-forming composition may be impregnated within the substrate ina variety of manners, such as spraying, knife coating, roll coating,curtain coating, spin coating, immersion coating, and combinationsthereof. After impregnation and prior to use, the substrate is at leastpartially saturated with the film-forming composition. The resultingarticle 10 may then be packaged in a sealed environment (individually orwith multiple articles) to prevent the solvent from evaporating. Whenthe user desires to apply an antimicrobial film on surface 12, the usermay wipe article 10 across surface 12 while applying a moderate amountof pressure. The applied pressure and the frictional force imposed bythe wiping action causes portions of the film-forming composition todeposit from the substrate of article 10. In particular, the polymer,the antimicrobial agent, and the solvent of the film-forming compositionare each deposited from the substrate of article 10. This is in contrastto conventional antimicrobial wipes, in which only an antimicrobial (andtypically a solvent) are deposited. By depositing the polymer with theantimicrobial agent and the solvent, the resulting antimicrobial filmcoated on surface 12 prevents the antimicrobial agent from beingimmediately washed away when surface 12 is cleaned.

The amount of film-forming composition extracted is dependent on thepressure applied, the extent of the wiping action, and the concentrationof the film-forming composition impregnated within the substrate. Insome embodiments, the amount of film-forming composition extracted isenough to form a dried antimicrobial film having a layer thickness onsurface 12 (after drying) ranging from about 1 micrometers to about 100micrometers, and particularly, ranging from about 2 micrometers to about50 micrometers. This can provide a suitable concentration ofantimicrobial agents to reduce the risk of microorganism contamination.

After use, article 30 may be discarded. Alternatively, if article 30retains a useable portion of the impregnated film-forming composition,article 30 may be reused to apply antimicrobial films to additionalsurfaces until the reservoir of film-forming composition impregnatedwithin substrate 12 is depleted. Accordingly, article 30 may be used asa disposable or semi-disposable wipe article by consumers. However,article 30 may also be re-impregnated with an additional supply of thefilm-forming composition for subsequent use. This increases the productlife of article 30.

After being applied to surface 12, the film-forming composition may bedried to remove the solvent. Suitable drying techniques include airdrying (e.g., forced or passive) at room temperature or elevatedtemperatures. The use of volatile solvents (e.g., isopropanol andacetone) can be useful for increasing the rate of drying. After drying,the resulting antimicrobial film is a thin, continuous film thatprovides antimicrobial protection to surface 12, as discussed above. Insome embodiments, the polymer matrix may also be fully or partiallycross-linked after being applied to surface 12 and dried. This canincrease the mechanical integrity of the antimicrobial film, therebyallowing the antimicrobial film to provide abrasion and chemicalresistance to surface 12 in addition to antimicrobial activity.

Examples of suitable layer thicknesses for antimicrobial film 10 (afterdrying) range from about 1 micrometer to about 500 micrometers, withparticularly suitable layer thicknesses ranging from about 2 micrometersto about 50 micrometers. Once applied, antimicrobial film 10 is a thin,durable film that provides antimicrobial protection to surface 12, asdiscussed above. In some embodiments, antimicrobial film 10 is also atransparent film, which allows the aesthetic qualities of the underlyingsurface (e.g., surface 12) to be visually observed through antimicrobialfilm 10.

As discussed above, after application to surface 12, antimicrobial film10 exhibits antimicrobial activity to reduce the microorganismcontamination of surface 12, and particularly, exhibits biocidalactivity. Examples of suitable levels of biocidal activity includemicrobial load reductions of at least about 90% for at least one of S.aureus (gram positive) and Ps. aeruginosa (gram negative) pathogens.Examples of even more suitable levels of biocidal activity includemicrobial load reductions of at least about 99% for at least one of S.aureus (gram positive) and Ps. aeruginosa (gram negative) pathogens.Examples of particularly suitable levels of biocidal activity includemicrobial load reductions of at least about 90% for both of S. aureus(gram positive) and Ps. aeruginosa (gram negative) pathogens. Finally,examples of even more particularly suitable levels of biocidal activityinclude microbial load reductions of at least about 99% for both of S.aureus (gram positive) and Ps. aeruginosa (gram negative) pathogens. The“microbial load reductions” herein refer to microbial load reductionsobtained pursuant to ASTM E2180-01.

Antimicrobial film 10 may also include an end-of-service indicator toprovide visual indication prompting the user to replace antimicrobialfilm 10. Examples of suitable end-of-service indicators includetime-temperature indicators and color changing dyes. An end-of-serviceindicator may be applied to antimicrobial film 10 in the form of a labelor paint to the corners of antimicrobial film 10 after antimicrobialfilm 10 is formed on surface 12. In some embodiments, the indicator iscalibrated to indicate a color change at about the time when thecorresponding antimicrobial layer 10 should be replaced (e.g., when theantimicrobial activity levels have substantially decreased or areexhausted).

Time-temperature indicators typically operate by chemical reactionmechanisms, diffusion mechanisms, and capillary driven, fluid-wickingmechanisms. Examples of suitable time-temperature indicators aredisclosed in Bommarito, et al., U.S. Pat. No. 6,741,523 (i.e.,microstructured time-dependent indicators) and Arens, et al., U.S. Pat.No. 5,667,303, both of which are incorporated by reference in theirentireties, and in The Wiley Encyclopedia of Packaging Technology,400-406 (John Wiley & Sons, 1986) under the section entitled “IndicatingDevices”. Examples of suitable commercially available time-temperatureindicators include those sold under the trade designations “MONITORMARK” from 3M Corporation, St. Paul, Minn.; “WARM MARK” from Dry PakIndustries, Studio City, Calif.; “FRESH CHECK” from Lifelines TechnologyInc., Morris Plains, N.J.; “VISTAB” from Visual Indicator Tag SystemsAB, Malmö, Sweden; and “TT MONITOR” from Avery Dennison Corporation,Pasadena, Calif.

FIG. 2 is a side sectional view of antimicrobial film 10 disposed onsurface 12, with remover composition 14 being deposited on antimicrobialfilm 10. Remover composition 14 is a solvent-based composition thatdissolves and/or swells the film-forming composition of antimicrobialfilm 10, as discussed below. Remover composition 14 may be deposited onantimicrobial film 10 in a spray form as illustrated in FIG. 2.Alternatively, remover composition 14 may be incorporated in a wipearticle that is wiped across antimicrobial film 10, thereby allowingremover composition 14 to dissolve and/or swell antimicrobial film 10during the wiping process.

Remover composition 14 may include one or more solvents that areeffective for dissolving the film-forming composition of antimicrobialfilm 10. Examples of suitable solvents for use in remover composition 14include water, aqueous alkaline solvents, volatile solvents (e.g.,acetone and isopropanol), glycols, and combinations thereof.

If the polymer in the film-forming composition of antimicrobial film 10is not cross-linked, then the solvent of remover composition 14 may beselected to dissolve antimicrobial film 10. In some embodiments, theremover solvent is selected to closely match the solubility parameter ofthe polymer used. The term “solubility parameter” herein refers to theHildebrand solubility parameter (δ), which is a solubility parameterrepresented by the square root of the cohesive energy density of amaterial, having units of (pressure)^(1/2), and being represented by thefollowing equation:

$\begin{matrix}{\delta = \sqrt{\left( \frac{{\Delta \; H} - {RT}}{V} \right)}} & (1)\end{matrix}$

where ΔH is the molar vaporization enthalpy of the material, R is theuniversal gas constant, T is the absolute temperature, and V is themolar volume of the solvent. Hildebrand solubility parameters aregenerally provided in conventional units of (calories/centimeter³)^(1/2)((cal/cm³)^(1/2)) and in SI units of megaPascals^(1/2) (MPa^(1/2)).

Hildebrand solubility parameters are tabulated for solvents in Barton,A. F. M., Handbook of Solubility and Other Cohesion Parameters, 2^(nd)Ed. CRC Press, Boca Raton, Fla., (1991), for monomers and representativepolymers in Polymer Handbook, 3^(rd) Ed., J. Brandrup & E. H. Immergut,Eds. John Wiley, NY pp. 519-557 (1989), and for many commerciallyavailable polymers in Barton, A. F. M., Handbook of Polymer-LiquidInteraction Parameters and Solubility Parameters, CRC Press, Boca Raton,Fla., (1990). Examples of suitable differences in Hildebrand solubilityparameters between the polymer in the film-forming composition ofantimicrobial film 10 and the solvent of remover composition 14 includedifferences of about 5.0 (cal/cm³)^(1/2) or less, with particularlysuitable differences in Hildebrand solubility parameters includingdifferences of about 2.0 (cal/cm³)^(1/2) or less, and with even moreparticularly suitable differences in Hildebrand solubility parametersincluding differences of about 1.0 (cal/cm³)^(1/2).

If the polymer in the film-forming composition of antimicrobial film 10is cross-linked, then the solvent of remover composition 14 may beselected to either dissolve (by chemically disrupting and breaking thecross-links) antimicrobial film 10, swell (by absorbing into thecross-linked polymer matrix) antimicrobial film 10, or a combinationthereof. Swelling takes place when the solvent of remover composition 14penetrates into a cross-linked polymer network through the surface ofantimicrobial film 10, which acts as a semi-permeable membrane. Thesolvent interacts with segments of the polymer network, which increasestheir mobility, disrupts the adhesion of the polymer segments to surface12, and facilitates the removal of the film-forming composition.Swelling will take place only if the free energy of mixing between thesolvent and the polymer segments is negative, where the free energy ofmixing is defined as:

ΔG _(m) =ΔH _(m) −TΔS _(m) =RT(n ₁ ln φ₁ +n ₂ ln φ₂+χ₁φ₂ n ₁)  (2)

where ΔG_(m) is the Gibbs free energy of mixing, ΔH_(m) is the enthalpyof mixing, T is the absolute temperature, ΔS_(m) is the entropy ofmixing, R is the universal gas constant, n₁ is the molar fraction of thesolvent in the swollen film, φ₁ is the weight fraction of the solvent,n₂ is molar fraction of the polymer in the swollen film, φ₂ the weightfraction of the polymer, and χ₁ is the Flory-Huggins interactionparameter. Equation (2) along with more detailed discussion of thetheory of polymer swelling can be found in Richards, E. G., AnIntroduction to Physical Properties of Large Molecules in Solution,IUPAB Biophysics Series, Cambridge University Press, Cambridge, (1980).

Examples of suitable solvents for use in remover composition 14 when thepolymer of the antimicrobial film is partially or fully cross-linked(i.e., polymers having reduced water solubility) include aqueousalkaline solvents (e.g., ammonia-containing solvents), volatile solvents(e.g., acetone and isopropanol), and combinations thereof. For example,when the film-forming composition of antimicrobial film 10 includes analkali soluble acrylic copolymer dispersion commercially available underthe trade designation “NEOCRYL BT-9” from DSM NeoResins, Wilmington,Mass., remover composition 14 may include a high pH solvent (e.g., anammonia solution or soap-containing aqueous solvent) to dissolve and/orswell the antimicrobial film 10. Examples of suitable concentrations ofthe solvent in remover composition 14 range from about 50% by weight to100% by weight, with particularly suitable total concentrations rangingfrom about 90% by weight to 100% by weight.

Remover composition 14 may also include surfactants and thickeners, andfoaming agents to modify wetting and flow properties. Examples ofsuitable surfactants and thickeners include those discussed above forthe film-forming composition of antimicrobial film 10. Examples ofsuitable total concentrations of surfactants and thickeners in removercomposition 14 range from about 1% by weight to about 20% by weight,with particularly suitable total concentrations ranging from about 5% byweight to about 10% by weight.

FIG. 3 is a top perspective view of hand 16 of a user removingantimicrobial film 10 from surface 12 with wipe article 18. Prior toremover composition 14 being deposited, antimicrobial film 10 isresistant to being removed from surface 12, as discussed above. As such,antimicrobial film 10 must be subjected to at least a first minimumfrictional force before being removed. The first minimum frictionalforce is greater than a moderate frictional force applied during asurface wiping with a wipe article. This prevents antimicrobial film 10from being undesirably removed until remover composition 14 isdeposited.

Remover composition 14, however, swells the polymer of the antimicrobialfilm 10 and/or breaks down the structural integrity of the polymer(i.e., dissolves the polymer), thereby allowing antimicrobial film 10 tobe readily removed from surface 12. As a result, after removercomposition 14 is deposited, antimicrobial film 10 may be removed by anapplication of a second minimum frictional force that is less than thefirst minimum frictional force. In some embodiments, the second minimumfrictional force is equal to or less than a moderate frictional forceapplied by a wiping motion with wipe article 18.

In some embodiments, as shown in FIG. 3, remover composition 14 may beimpregnated within wipe article 18. In this embodiment, the user mayforgo a separate step of depositing remover composition 14 ontoantimicrobial film 10. As the user applies frictional force toantimicrobial film 10 with wipe article 18, remover composition 14 isextracted from wipe article 18 and deposits onto antimicrobial film 10.Remover composition 14 then dissolves and/or swells the polymer in thefilm-forming composition of antimicrobial film 10, thereby allowingantimicrobial film 10 to be wiped away from surface 12 after severalstrokes with wipe article 18. Accordingly, wipe article 18 is adisposable article that reduces time and effort the user must undertaketo remove antimicrobial film 10 from surface 12.

After antimicrobial film 10 is removed from surface 12, a fresh coatingof antimicrobial film 10 may be coated on surface 12, pursuant to thecoating techniques discussed above in FIG. 1. This may provideantimicrobial protection to surface 12 for extended periods of time. Forexample, when substantially all of the antimicrobial agents are releasedfrom a first coating of antimicrobial film 10, a user may depositremover composition 14 on antimicrobial film 10, and wipe the firstcoating of antimicrobial film 10 away. The user may then coat surface 12with a second coating of antimicrobial film 10 to provide a renewedsource of protection against microbial contamination.

EXAMPLES

The present invention is more particularly described in the followingexamples that are intended to be illustrative and not limiting, sincenumerous modifications and variations within the scope of the presentinvention will be apparent to those skilled in the art. Examples 1-20are working examples, and Examples 21-27 are prophetic examples.

Unless otherwise noted, all parts, percentages, and ratios reported inthe following examples are on a weight basis, and all reagents used inthe examples were obtained, or are available, from the chemicalsuppliers described below, or may be synthesized by conventionaltechniques.

The following compositional abbreviations are used in the followingExamples:

-   “AgION”: A silver-containing inorganic zeolite food-grade    antimicrobial agent, type AJ, which contains 2.5% silver, and which    is commercially available under the trade designation “AgION”    Antimicrobial from AgION Technologies, Inc., Wakefield, Mass.-   “Triclosan”: Triclosan antimicrobial agent, commercially available    from Ciba Specialty Chemicals., Tarrytown, N.Y.-   “Lauricidin solution”: A fluid solution containing 20.0% glycerol    monolaurate fatty acid monoester (commercially available under the    trade designation “LAURICIDIN” from Med-Chem Laboratories, East    Lansing, Mich.), 10.0% 2-hydroxybenzoic (salicylic) acid    (HOC₆H₈CO₂H) with a formula weight of 138.1 (commercially available    from Sigma-Aldrich Chemical Company, Saint Louis, Mo.), and 10.0%    dioctylsulfosuccinate (DOSS) surfactant (commercially available from    Alfa Aesar, Ward Hill, Mass.) in isopropanol.-   “Bardac 205M”: A quaternary ammonium compound commercially available    under the trade designation “BARDAC 205M” from Lonza Group Ltd.,    Valais, Switzerland.-   “Bardac 208M”: A quaternary ammonium compound commercially available    under the trade designation “BARDAC 208M” from Lonza Lonza Group    Ltd., Valais, Switzerland.-   “Zn Pyrithione”: Zinc pyrithione, which is synthesized from    2-mercaptopyridine N-oxide salt and zinc acetate, both of which are    commercially available from Sigma-Aldrich Chemical Company, Saint    Louis, Mo.-   “Silver oxide”: Silver oxide (AgO) having a formula weight of 123.9,    commercially available from Alfa Aesar, Ward Hill, Mass.-   “Vantocil P”: A    poly(iminoimidocarbonylimidocarbonyliminohexa-methylene    hydrochloride), pH 5-6, 20% by weight active in water, commercially    available under the trade designation “VANTOCIL P” from Arch    Chemicals, Inc., Norwalk, Conn.-   “Vantocil IB”: A    poly(iminoimidocarbonylimidocarbonyliminohexa-methylene    hydrochloride), pH 4-5, 20% by weight active in water, commercially    available under the trade designation “VANTOCIL IB” from Arch    Chemicals, Inc., Norwalk, Conn.-   “Metasol TK 25”: A thiabendazole-based agent, commercially available    under the trade designation “METASOL TK 25” from Lanxess    Corporation, Pittsburgh, Pa.-   “AgION SilverClene 24”: A silver-containing inorganic zeolite    food-grade antimicrobial agent, which contains 0.003% silver, 4.8%    citric acid, and which is commercially available under the trade    designation “AGION SILVERCLENE 24” Antimicrobial from AgION    Technologies, Inc., Wakefield, Mass.-   “CHG”: 20% chlorhexidine gluconate by weight in water, commercially    available from Xttrium Laboratories, Inc., Chicago, Ill.-   “Ammonium Carbonate”: Ammonium carbonate salt, commercially    available from Sigma-Aldrich, Milwaukee, Wis.-   “PVOH”: A polyvinyl alcohol polymer with molecular weight of 180,000    Daltons, commercially available from Sigma-Aldrich Chemical Company,    Saint Louis, Mo.-   “PVP-K90”: A polyvinylpyrrolidone polymer with molecular weight of    90,000 Daltons, which is commercially available under the trade    designation “PVP-K90” from Peakchem, ZheJiang, China.-   “R-960”: A water based urethane dispersion containing 33% solids,    commercially available under the trade designation “NEOREZ R-960”    from DSM-NeoResins, Wilmington, Mass.-   “RU21-075”: A water-based polyurethane dispersion containing 40%    solids, commercially available under the trade designation    “RU21-075” from Stahl USA, Peabody, Mass.-   “Sancure 815”: A water-based polyurethane dispersion, commercially    available under the trade designation “SANCURE 815” from Noveon,    Inc., Cleveland, Ohio.-   “PVP”: A polyvinylpyrrolidone (2% solids in water), commercially    available under the trade designation “K-12” from International    Specialty Products, Wayne, N.J.-   “Incorez 835/494”: A soft aliphatic polyurethane dispersion (5% in    water), commercially available under the trade designation “INCOREZ    835/494” from Industrial Copolymers, Ltd., Lancashire, England.-   “Incorez 835/140”: A hard aliphatic polyurethane dispersion (5% in    water), commercially available under the trade designation “INCOREZ    835/140” from Industrial Copolymers, Ltd., Lancashire, England.-   “Cydrothane HP 5035”: A hard aromatic polyurethane dispersion (5% in    water), commercially available under the trade designation    “CYDROTHANE HP 5035” from Cytek Industries, Inc., West Paterson,    N.J.-   “Cydrothane HP 1035”: A soft aromatic polyurethane dispersion (5% in    water), commercially available under the trade designation    “CYDROTHANE HP 1035” from Cytek Industries, Inc., West Paterson,    N.J.-   “GlossTek”: A reactive aliphatic polyurethane, commercially    available under the trade designation “GLOSSTEK” from Ecolab, St.    Paul, Minn.-   “Stance”: A zinc cross-linked acrylic plus polyethylene wax    dispersion, commercially available under the trade designation    “STANCE” from 3M Corporation, St. Paul, Minn.-   “Cornerstone”: An acrylic floor sealer/finish (25% in water),    commercially available under the trade designation “CORNERSTONE”    from 3M Corporation, St. Paul, Minn.-   “NeoCryl XK-98”: A self cross-linking acrylic dispersion    commercially available under the trade designation “NEOCRYL XK-98”    from DSM NeoResins, Wilmington, Mass.-   “B66 acrylic resin”: An acrylic resin commercially available under    the trade designation “SPEC-CRETE SUPERSEAL B66” from Farfan &    Mendes Ltd., Georgetown, Guyana.-   “XK-90”: A 40% acrylic cross-linkable polymer dispersion in water,    commercially available under the trade designation “NEOPAC XK-90”    from DSM-NeoResins, Wilmington, Mass.-   “XR-2500”: A polyfunctional aziridine cross-linker commercially    available under the trade designation “XR-2500” from Stahl USA,    Peabody, Mass.-   “XL-A”: A combination of 76 parts ethanol, 22.8 parts of an    aziridine cross-linker commercially available under the trade    designation “CX-100” from DSM NeoResins, Wilmington, Mass., and 1.2    parts of a surfactant commercially available under the trade    designation “SURFYNOL 104PA” from Air Products and Chemicals, Inc.    Allentown, Pa. The combined mixture was blended for 20 minutes under    high shear.-   “Exxate 800”: An oxo-alkyl acetic ester solvent commercially    available under the trade designation “EXXATE 800” from Exxon Mobil    Corporation, Houston, Tex.-   “PET film”: A polyethylene terephthalate film with acrylate-primed    layer, commercially available from Mitsubishi, Japan.-   “BOPP Film”: A biaxially-oriented, corona-treated, polypropylene    film available from 3M Corporation, St. Paul, Minn.

Examples 1 and 2

Antimicrobial films of Examples 1 and 2 were each prepared pursuant tothe following procedure. A PVOH solution was prepared by combining 5parts of PVOH with 95 parts water, and shaking the mixture in a warmbath for 24 hours to fully dissolve the PVOH. 30 parts of the PVOHsolution were then mixed with 0.2 parts of an antimicrobial agent (AgIONfor Example 1, and Triclosan for Example 2). The resulting film-formingcomposition was then coated onto a corona-treated BOPP film using aMeyer rod #36, and dried at 55° C. for 5 minutes to form theantimicrobial film.

The antimicrobial films of Examples 1 and 2 were each tested for“microbial load reduction” pursuant to ASTM E2180-01, which involvedinoculation of a molten (45° C.) agar slurry with a standardized cultureof bacterial cells. A thin layer of the inoculated agar slurry (0.5milliliter) was then pipetted onto the test material and the untreatedcontrol material. Samples were tested in duplicate using Staphylococcusaureus (ATCC 6538) and Pseudomonas aeruginosa (ATCC 9027). After 24hours, surviving microorganisms were recovered via elution of the agarslurry inoculum from the test substrate into D/E Neutralizing broth andextracted by sonication and vortexing. Serial dilutions were then made,and pour plates were made of each dilution. Agar plates were incubatedfor 48 hours at 28° C.±1° C. Bacterial colonies from each dilutionseries were then counted and recorded. Calculation of percent reductionof bacteria from treated versus untreated samples was then made. Apercent reduction greater than 99.95% was reported as 100%.

Table 1 provides the microbial load reduction results for theantimicrobial films of Examples 1 and 2.

TABLE 1 % Reduction Antimicrobial % Reduction S. aureus Ps. aeruginosaExample Agent (Gram Positive) (Gram Negative) Example 1 AgION 100 100Example 2 Triclosan 100 0

The results shown in Table 1 illustrate the good antimicrobial activityprovided by the antimicrobial films of Examples 1 and 2. Theantimicrobial film of Example 2 exhibited poor gram negative results,which is typical for Triclosan antimicrobial agents.

The antimicrobial films of Examples 1 and 2 were also tested for ease ofremoval with a remover composition. Synthetic wipes (commerciallyavailable under the trade designation “TX1009 ALPHAWIPE” from ITWTexwipe, Upper Saddle River, N.J.) were used for the evaluation. Foreach antimicrobial film, a 4″×4″ piece of a synthetic wipe was saturatedwith water at room temperature and rubbed over the antimicrobial film.For each antimicrobial film of Examples 1 and 2, the film was removedfrom the BOPP substrate after two strokes with the wet synthetic wipe.Based on visual observations, the first stroke appeared to wet andsoften the antimicrobial film due to the antimicrobial film swelling,and the second stroke removed it in a solid form. This demonstrates thatthe antimicrobial film was swelled by water but did not dissolve inwater and was durable enough to substantially withstand dissolution inwater due to the relatively high molecular weight of PVOH that was used.

Examples 3-8

Antimicrobial films of Examples 3-8 were each prepared pursuant to thefollowing procedure. A solution was prepared by dissolving PVP-K90 andan antimicrobial agent in a 50:50 solution of isopropanol and methylethyl ketone. The solution was then coated on a non-treated polyethyleneterephthalate substrate using a Meyer rod #9. The coated film was driedat room temperature for 20 minutes and then dried at 80° C. for 10minutes.

The antimicrobial films of Examples 3-8 were each tested for “microbialload reduction” pursuant to the procedure discussed above for Examples 1and 2. A control coating of PVP-K90 without an antimicrobial agent wasused as a control.

TABLE 2 % Percent by Reduction % Reduction Weight of S. aureus Ps.aeruginosa Antimicrobial Antimicrobial (Gram (Gram Example Agent AgentPositive) Negative) Example 3 Lauricidin 6 100 0 solution Example 4Bardac 208M 6 100 100 Example 5 Bardac 205M 6 100 100 Example 6Triclosan 6 100 0 Example 7 AgION 5 100 100 Example 8 Zn Pyrithione 683.8 97.7

The results shown in Table 2 illustrate the good antimicrobial activityprovided by the antimicrobial films of Examples 3-8. Accordingly, avariety of antimicrobial agents may be used with the present invention.

Examples 9-15 and Comparative Examples A and B

Antimicrobial films of Examples 9-15 and Comparative Examples A and Bwere each prepared pursuant to the following procedure. A solution wasprepared by combining an antimicrobial agent, a cross-linking agent, apolymer dispersion, and 5 parts of water. For the films of Examples 9-11and Comparative Example A, the polymer dispersion was 20 parts of R-960,and for the films of Examples 12-15 and Comparative Example B, thepolymer dispersion was 10 parts of RU21-075. Table 3 provides theantimicrobial agents and cross-linking agents combined in the solutionsfor the films of Examples 9-15 and Comparative Examples A and B.

TABLE 3 Parts of Antimicrobial Antimicrobial Cross- Parts of ExampleAgent Agent Linker Cross-Linker Comparative None 0.0 None 0.0 Example AExample 9 AgION 0.5 XR-2500 0.2 Example 10 AgION 0.5 XL-A 4.0 Example 11Triclosan 5.0 XL-A 4.0 Comparative None 0.0 None 0.0 Example B Example12 AgION 0.5 XL-A 2.0 Example 13 AgION 0.5 XR-2500 0.1 Example 14Triclosan 1.0 XL-A 2.0 Example 15 Triclosan 1.0 XR-2500 0.1

The resulting film-forming compositions were then coated onto acorona-treated BOPP film using a Meyer rod #6, and dried at 55° C. for 5minutes to form the antimicrobial film. The antimicrobial films ofExamples 9-15 and Comparative Examples A and B were then each tested for“microbial load reduction” pursuant to ASTM E2180-01, as discussed abovefor Examples 1 and 2. Table 4 provides the microbial load reductionresults for the antimicrobial films of Examples 9-15 and ComparativeExamples A and B.

TABLE 4 % % Reduction Reduction Ps. Parts of S. aureus aeruginosaAntimicrobial Antimicrobial (Gram (Gram Example Agent Agent Positive)Negative) Comparative None 0.0 0.0 0.0 Example A Example 9 AgION 0.599.7 100.0 Example 10 AgION 0.5 99.4 100.0 Example 11 Triclosan 5.0 69.70.0 Comparative None 0.0 0.0 0.0 Example B Example 12 AgION 0.5 98.9100.0 Example 13 AgION 0.5 96.0 100.0 Example 14 Triclosan 1.0 89.0 0.0Example 15 Triclosan 1.0 41.0 19.0

The results shown in Table 4 further illustrate the good antimicrobialactivity provided by the antimicrobial films of the present invention.As discussed above, the antimicrobial films containing Triclosan (i.e.,Examples 11, 14, and 15) exhibited poor gram negative results, which istypical for Triclosan antimicrobial agents. In addition, theantimicrobial films containing Triclosan exhibited relatively poor grampositive results. This could be due to the triclosan interacting morestrongly with the polymer of the antimicrobial film.

The antimicrobial films of Examples 9, 10, 12, and 13, and ComparativeExamples A and B were also tested for ease of removal from the BOPP filmwith a remover composition pursuant to the following procedure. Eachsample was sprayed with WINDEX-brand glass cleaner solution, which iscommercially available from SC Johnson & Son, Inc., Racine, Wis. After a30 second waiting period, the sample was then wiped three strokes undermoderate force with a paper towel, and the amounts of the film removedwere estimated by visual observation. Table 5 provides the percentremoval for the antimicrobial films of Examples 9, 10, 12, and 13, andComparative Examples A and B.

TABLE 5 Polymer Matrix Example Material Cross-Linker % RemovalComparative Example A R-960 None 100% Example 9 R-960 XR-2500 10 Example10 R-960 XL-A 10 Comparative Example B RU21-075 None 100 Example 12RU21-075 XL-A 100 Example 13 RU21-075 XR-2500 90

The results shown in Table 5 illustrate the difference in removal basedon the type of cross-linked polymer dispersion used. This is shown bythe films of Examples 9 and 10, which used the R-960. Accordingly, astronger solvent is more desirable for use with the films of Examples 9and 10. In comparison, however, the films of Examples 12 and 13exhibited low resistances to the alkali environment, and were readilyremoved. As such, ammonia-based solvents are suitable as removercompositions for antimicrobial films containing cross-linked RU21-075polymer matrix materials.

Example 16

An antimicrobial film of Example 16, which is an example of a selfcross-linking polymer, was prepared pursuant to the following procedure.A mixture was formed by combining 95 parts of NeoCryl XK-98 with 5 partsAgION. The mixture was then coated onto BOPP film using a Meyer rod #14and dried in an oven at 60° C. for 5 minutes. While drying, the NeoCrylXK-98 polymer self cross-linked via a condensation reaction. Theresulting antimicrobial film of Example 16 was then tested for“microbial load reduction” pursuant to ASTM E2180-01, as discussed abovefor Examples 1 and 2. The film of Example 16 exhibited a 100% microbialload reduction for both S. aureus (gram positive) and Ps. aeruginosa(gram negative).

The antimicrobial film of Example 16 was also tested for ease of removalfrom the BOPP film with remover compositions. A first sample of the filmwas sprayed with water and a second sample of the film was sprayed withWINDEX-brand glass cleaner solution, which is commercially availablefrom SC Johnson & Son, Inc., Racine, Wis. After a 30 second waitingperiod, the samples were then wiped three strokes under moderate forcewith a paper towel, and the amount of the film removed was observed. Forthe water-sprayed sample, the film was unaffected by the water and wasnot removed. This is due to the cross-linked structure of the film. Incontrast, for the WINDEX-sprayed sample, the film was readily removed.As a result, the antimicrobial film of Example 16 is suitable for use ona variety of surfaces that are treated with water. The cross-linkedpolymer matrix prevents the antimicrobial film of Example 16 from beingremoved during normal washing operations (e.g., washing a surface with awetted towel or sponge), but is readily removed when a WINDEX-basedremover composition is applied.

Example 17

An antimicrobial film of Example 17, which is an example of AgION silverin a solvent-borne formulation, was prepared pursuant to the followingprocedure. A mixture was prepared by combining 2 parts by weight of B66acrylic resin, 0.2 parts AgION, and 8 parts Exxate 800 solvent. Themixture was stirred for one hour to dissolve the B66 acrylic resin anddisperse the AgION. The resulting mixture was then coated on a BOPP filmusing a Meyer rod #26. The film was then dried in an oven at 55° C. for5 minutes. The coating appearance was transparent, but non-uniform witha blotchy surface.

The resulting antimicrobial film of Example 17 was then tested for“microbial load reduction” pursuant to ASTM E2180-01, as discussed abovefor Examples 1 and 2. The film of Example 17 exhibited a 68.4% microbialload reduction for S. aureus (gram positive) and a 100.0% microbial loadreduction for Ps. aeruginosa (gram negative). Additionally, a wipe wassaturated with MEK (methyl ethyl ketone) and used to rub the film. Afterthree strokes, about 80% of the film was removed, as estimated by visualobservation.

Example 18

An antimicrobial film of Example 18, which is an example of AgION silverin a water-based formulation, was prepared pursuant to the followingprocedure. A mixture was prepared by combining 8.6 parts XK-90 (acryliccross-linkable polymer dispersion in water), 0.6 parts XL-Across-linker, and 0.4 parts AgION. The mixture was stirred for a fewminutes until homogeneous in appearance. The composition was coated ontoa BOPP film using a Meyer rod #14. The film was then dried at 55° C. for5 minutes. The resulting film appearance was hazy, but uniform.

The resulting antimicrobial film of Example 18 was then tested for“microbial load reduction” pursuant to ASTM E2180-01, as discussed abovefor Examples 1 and 2. The film of Example 17 exhibited a 100.0%microbial load reduction for both S. aureus (gram positive) and Ps.aeruginosa (gram negative).

To assess the ease of film removal, a spray of water, WINDEX-brand glasscleaner solution, soapy warm water, and MEK were applied to the film.After allowing each solvent to interact with the film for 10 minutes,the film plus solvent was wiped using a KemWipe and applying moderateforce. The film was unaffected under the areas saturated with water,WINDEX-brand glass cleaner solution, and soapy warm water. Most of thefilm was removed under the area saturated with MEK. This shows that thefilm-forming composition in this example exhibits high durability andrequires an aggressive solvent for the remover composition.

Example 19

An antimicrobial film of Example 19 was prepared pursuant to thefollowing procedure. A silver oxide solution was initially prepared bycombining 5 parts ammonium carbonate salt with 95 parts water, andmixing until the salt was dissolved. To this solution, 1 part silveroxide was added. The mixture was stirred at 60° C. for one hour untilthe silver oxide was dissolved. A mixture was then prepared by combining20 parts by weight of XK-90 binder material, 1 part silver oxidesolution, 2 parts XL-A cross-linker, and 12 parts water. The mixture wasshaken by hand to form a uniform dispersion, and then coated on a PETfilm using a Meyer rod #12. The film was then dried at in an oven at 55°C. for 5 minutes and cured. The resulting film appearance wastransparent and uniform, with a slight brown tint due to the presence ofthe silver oxide. This color tint can be beneficial for allowing a userto visually determine the presence and uniformity of the coating.

The resulting antimicrobial film of Example 10 was then tested for“microbial load reduction” pursuant to ASTM E2180-01, as discussed abovefor Examples 1 and 2. The film of Example 28 exhibited a 51.2% microbialload reduction for S. aureus (gram positive) and a 100.0% microbial loadreduction for Ps. aeruginosa (gram negative).

Example 20

An antimicrobial film of Example 20, which included a fast-actingantimicrobial agent, was prepared pursuant to the following procedure. Asolvent of 60 parts ethyl alcohol and 40 parts water was initiallyprepared. A mixture was then prepared by adding 6 parts PVOH polymer tothe solvent. The mixture was shaken in warm bath until the PVOH wasdissolved, which was about 24 hours. After the shaking process, 1 partAgION was added to the mixture. The resulting mixture exhibited instantbacterial kill capabilities due to the high content of ethyl alcohol,while the coated composition also provided for longer-term antimicrobialactivity after the alcohol evaporates as shown above in Example 1. Thisillustrates the versatility of the present invention for reducingpathogen contamination.

Examples 21-27

Examples 21-27 illustrate prophetic polymer-antimicrobial agentcombinations that can be used to form water-insoluble, biocidalantimicrobial films according to the present invention. Table 6 providesthe listing of the polymer-antimicrobial agent combinations for Examples21-27. For each of Examples 21-27, a plurality of antimicrobial agentscan be used alone or in combination and are listed in a comma-delimitedmanner to signify this. The following letter codes are used toabbreviate the antimicrobial agents in Table 6: A=Vantocil IB,B=Triclosan, C=AgION SilverClene 24, and D=CHG.

TABLE 6 Antimicrobial Example Polymer Agent Example 21 Cornerstone (25%in water) A, B, C, D Example 22 Incorez 835/494 (5% in water) C, DExample 23 Incorez 835/140 (5% in water) C, D Example 24 Cydrothane HP5035 (5% in water) C, D Example 25 Cydrothane HP 1035 (5% in water) C, DExample 26 GlossTek C, D Example 27 Stance A, B, C, D

The embodiments described above and illustrated in the figures arepresented by way of example only and are not intended as a limitationupon the concepts and principles of the present invention. As such, itwill be appreciated by one having ordinary skill in the art that variouschanges in form and detail are possible without departing from thespirit and scope of the present invention. Various features and aspectsof the invention are set forth in the following claims.

1. A film-forming composition comprising: a polymer comprising at leastone of polyvinyl alcohol having an effective molecular weight, acrylic,urethane, and a combination thereof; an effective amount of anantimicrobial agent dispersed within the polymer, the antimicrobialagent comprising at least one of a fatty acid monoester, a fatty acidmonoether, and a combination thereof; and a solvent, wherein thefilm-forming composition includes a solid concentration of no greaterthan about 50% by weight, the film-forming composition forming awater-insoluble, biocidal antimicrobial film when applied to a surface.2. The film-forming composition of claim 1, wherein the antimicrobialagent constitutes about 0.1% by weight to about 20% by weight of thefilm-forming composition.
 3. The film-forming composition of claim 1,wherein the antimicrobial agent constitutes about 1% by weight to about10% by weight of the film-forming composition.
 4. The film-formingcomposition of claim 1, wherein the film-forming composition furthercomprises a fast-acting antimicrobial agent selected from the groupconsisting of quaternary ammonium salts, benzalkonium chlorides,biguanide compounds, alcohols, bleach, hydrogen peroxide, urea hydrogenperoxide, hydrogen peroxide stabilized in a sodium pyrophosphate matrix,hydrogen peroxide chelated in polyvinylpyrrolidone, and combinationsthereof.
 5. An antimicrobial film comprising: a polymer having aneffective molecular weight, such that the antimicrobial film iswater-insoluble; and an effective amount of an antimicrobial agent, suchthat the antimicrobial film is biocidal, the antimicrobial agentcomprising at least one of a fatty acid monoester, a fatty acidmonoether, and a combination thereof, wherein the antimicrobial filmincludes about 70% by weight to about 99.9% by weight of the polymer. 6.The antimicrobial film of claim 5, wherein the antimicrobial filmexhibits microbial load reductions of at least about 99% for grampositive pathogens and gram negative pathogens, when tested pursuant toASTM E2180-01.
 7. The antimicrobial film of claim 5, wherein theantimicrobial film comprises a cross-linked polymer.
 8. Theantimicrobial film of claim 5, wherein the antimicrobial film comprisesan end-of-service indicator.
 9. A method of verifying the presence of anantimicrobial film, the method comprising: providing the antimicrobialfilm of claim 5 applied to a surface; wetting the surface; and based onwhether a color change occurred upon wetting the surface, determiningwhether the antimicrobial film is still intact on the surface.
 10. Theantimicrobial film of claim 5, wherein the antimicrobial film includesabout 90% by weight to about 99% by weight of the polymer.